The present invention pertains to data transmission between telecommunications switching systems via digital spans and more particularly to a circuit within a telecommunications switching system for detecting proper framing and super framing for a number of digital spans.
In modern telecommunications switching, it is necessary to transmit large amounts of data rapidly between switching systems. To this end, digital spans are utilized to connect switching systems and to transmit this data. These digital spans may be T1 or T2 carriers using DS1 or DS2 data formats, respectively. These digital spans transmit data at high speeds, serially. The data is transmitted by one switching system and received by another. Since a particular switching system may be connected to a number of others, each switching system may have a number of digital spans from which it receives data.
These digital spans contain framing and synchronizing information. Since high frequency signals are subject to drifting, periodically the digital spans may lose proper framing and synchronization. This problem is magnified when a switching system must maintain proper framing and synchronization for a number of digital spans.
In addition, the Federal Communications Commission provides regulations which mandate the time duration that a digital span may be without proper framing and synchronization.
Accordingly, it is the object of the present invention to provide an efficient and quick operating circuit for digital span frame detection.